Vector Help (1 Viewer)

ALOZZZ

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Hey guys,
I am having trouble with this question:
Determine the magnitude and direction of 2i in exact form. I have attempted it and the magnitude is 2, but when I tried to calculate the direction I got 0 and the answer is 90.
 

Trebla

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Draw an arrow from the origin to the point on the complex plane. The magnitude is the length of the arrow from the origin and the angle is between the arrow and the positive x-axis.
 

ALOZZZ

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What about this question: Determine the magnitude and direction of 5i in exact form. Would the same method apply?
 

Qeru

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What about this question: Determine the magnitude and direction of 5i in exact form. Would the same method apply?
Even easier as the vector points 5 units up at an angle of 90 degrees to the positive x-axis.
 

Trebla

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What about this question: Determine the magnitude and direction of 5i in exact form. Would the same method apply?
I wouldn’t call it a “method” per se. It’s just the definitions of magnitude and direction of a vector.

A vector is simply a means to specify the magnitude and direction of something (e.g. a force). It is represented by an arrow. The length of the arrow tells you the magnitude and the angle of the arrow (relative to positive x-axis by convention) tells you the direction.

How you go about finding the magnitude and direction depends on the question (i.e. method). If it’s just pointing vertical or horizontal then the direction/angle should be obvious, but if it’s at some incline then some trig work is involved to find the angle.
 

A1La5

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Direction is zero? Thats clearly wrong which textbook are you using?
The vector 5i + 0j has no vertical component. The magnitude of 5i is 5 and the direction is zero degrees from the positive x axis.

Unless OP is referring to "i" in terms of complex numbers in which case yeah the direction would be 90 degrees.
 
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Trebla

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Ah I see where the confusion lies. Are we talking about i in the context of complex numbers or in terms of unit vectors?
 

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